Putting Together a Temperature Controller

I’ve been told by many other homebrewers that one of the most important things in homebrewing is repeatability. If you can’t repeat your process exactly and only change one variable at a time, how are you ever going to dial in a recipe and/or diagnose then reduce faults?

So one of the most variable parts of my brewing process thus far has been fermentation temperature control – basically I had none. I started off with the fermenter sitting in the corner of the room, meaning that the temperature would fluctuate based on what the central heating is currently setting the room temperature at or the time of year. I then migrated to placing the fermenter in a large flexible plastic bucket (something like this) filled with water. This did a good job at stabilising large temperature fluctuations, but the overall temperature was still dependent on the room temperature and the time of the year.

So enough was enough, I had a spare fridge in the garage which was going to become my fermentation chamber, and a tube heater borrowed from a buddy at work, now all I needed was a temperature controller…

Here’s the shopping list – I got the STC-1000 is from eBay and everything else from Maplin:

* 2m for main power lead, 1m each for heater/fridge plug sockets, the remaining cable I striped and separated out the cores to use for the internal wiring in the box.

To put the thing together I cut holes into the box using a Dremel hand saw and a drill, then simply followed the instructions in this great video, but instead of using heat shrink wraps, I used the terminal blocks and wired the mains cables into one side (coming directly from the plug connector) and the wires from the controller to the other side:

And this is the final result!

I’ve got in use on a batch as I type this and it’s happily holding the fermentation at 19 ºC. 🙂